[v4,7/9] power: reset: at91-reset: add reset_controller_dev support

SAMA7G5 reset controller has 5 extra lines that goes to different devices
(3 lines to USB PHYs, 1 line to DDR controller, 1 line to DDR PHY
controller). These reset lines could be requested by different controller
drivers (e.g. USB PHY driver) and these controllers' drivers could
assert/deassert these lines when necessary. Thus add support for
reset_controller_dev which brings this functionality.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/power/reset/at91-reset.c | 106 +++++++++++++++++++++++++++++--
 1 file changed, 102 insertions(+), 4 deletions(-)

Hi,

On Wed, Jun 08, 2022 at 11:39:40AM +0300, Claudiu Beznea wrote:
> SAMA7G5 reset controller has 5 extra lines that goes to different devices
> (3 lines to USB PHYs, 1 line to DDR controller, 1 line to DDR PHY
> controller). These reset lines could be requested by different controller
> drivers (e.g. USB PHY driver) and these controllers' drivers could
> assert/deassert these lines when necessary. Thus add support for
> reset_controller_dev which brings this functionality.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>  drivers/power/reset/at91-reset.c | 106 +++++++++++++++++++++++++++++--
>  1 file changed, 102 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> index 1b2aca3f490d..e25d8d38a2f8 100644
> --- a/drivers/power/reset/at91-reset.c
> +++ b/drivers/power/reset/at91-reset.c
> @@ -17,10 +17,13 @@
>  #include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/reboot.h>
> +#include <linux/reset-controller.h>
>  
>  #include <soc/at91/at91sam9_ddrsdr.h>
>  #include <soc/at91/at91sam9_sdramc.h>
>  
> +#include <dt-bindings/reset/sama7g5-reset.h>
> +
>  #define AT91_RSTC_CR	0x00		/* Reset Controller Control Register */
>  #define AT91_RSTC_PROCRST	BIT(0)		/* Processor Reset */
>  #define AT91_RSTC_PERRST	BIT(2)		/* Peripheral Reset */
> @@ -65,7 +68,10 @@ enum reset_type {
>   * struct at91_reset - AT91 reset specific data structure
>   * @rstc_base:		base address for system reset
>   * @ramc_base:		array with base addresses of RAM controllers
> + * @dev_base:		base address for devices reset
>   * @sclk:		slow clock
> + * @rcdev:		reset controller device
> + * @lock:		lock for devices reset register access
>   * @nb:			reset notifier block
>   * @args:		SoC specific system reset arguments
>   * @ramc_lpr:		SDRAM Controller Low Power Register
> @@ -73,12 +79,17 @@ enum reset_type {
>  struct at91_reset {
>  	void __iomem *rstc_base;
>  	void __iomem *ramc_base[2];
> +	void __iomem *dev_base;
>  	struct clk *sclk;
> +	struct reset_controller_dev rcdev;
> +	spinlock_t lock;
>  	struct notifier_block nb;
>  	u32 args;
>  	u32 ramc_lpr;
>  };
>  
> +#define to_at91_reset(r)	container_of(r, struct at91_reset, rcdev)
> +
>  /**
>   * struct at91_reset_data - AT91 reset data
>   * @reset_args:		SoC specific system reset arguments
> @@ -216,6 +227,87 @@ static const struct of_device_id at91_reset_of_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, at91_reset_of_match);
>  
> +static int at91_reset_update(struct reset_controller_dev *rcdev,
> +			     unsigned long id, bool assert)
> +{
> +	struct at91_reset *reset = to_at91_reset(rcdev);
> +	unsigned long flags;
> +	u32 val;
> +
> +	spin_lock_irqsave(&reset->lock, flags);
> +	val = readl_relaxed(reset->dev_base);
> +	if (assert)
> +		val |= BIT(id);
> +	else
> +		val &= ~BIT(id);
> +	writel_relaxed(val, reset->dev_base);
> +	spin_unlock_irqrestore(&reset->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int at91_reset_assert(struct reset_controller_dev *rcdev,
> +			     unsigned long id)
> +{
> +	return at91_reset_update(rcdev, id, true);
> +}
> +
> +static int at91_reset_deassert(struct reset_controller_dev *rcdev,
> +			       unsigned long id)
> +{
> +	return at91_reset_update(rcdev, id, false);
> +}
> +
> +static int at91_reset_dev_status(struct reset_controller_dev *rcdev,
> +				 unsigned long id)
> +{
> +	struct at91_reset *reset = to_at91_reset(rcdev);
> +	u32 val;
> +
> +	val = readl_relaxed(reset->dev_base);
> +
> +	return !!(val & BIT(id));
> +}
> +
> +static const struct reset_control_ops at91_reset_ops = {
> +	.assert = at91_reset_assert,
> +	.deassert = at91_reset_deassert,
> +	.status = at91_reset_dev_status,
> +};
> +
> +static int at91_reset_of_xlate(struct reset_controller_dev *rcdev,
> +			       const struct of_phandle_args *reset_spec)
> +{
> +	if (reset_spec->args[0] < SAMA7G5_RESET_USB_PHY1 ||
> +	    reset_spec->args[0] > SAMA7G5_RESET_USB_PHY3)
> +		return -EINVAL;

Can you move the min/max info to the devce info struct, so that
this stays as generic as the name suggests (and is prepared for
future devices)?

-- Sebastian

> +	return reset_spec->args[0];
> +}
> +
> +static int at91_rcdev_init(struct at91_reset *reset,
> +			   const struct at91_reset_data *data,
> +			   struct platform_device *pdev)
> +{
> +	if (!data->n_device_reset)
> +		return 0;
> +
> +	reset->dev_base = devm_of_iomap(&pdev->dev, pdev->dev.of_node, 1,
> +					NULL);
> +	if (IS_ERR(reset->dev_base))
> +		return -ENODEV;
> +
> +	spin_lock_init(&reset->lock);
> +	reset->rcdev.ops = &at91_reset_ops;
> +	reset->rcdev.owner = THIS_MODULE;
> +	reset->rcdev.of_node = pdev->dev.of_node;
> +	reset->rcdev.nr_resets = data->n_device_reset;
> +	reset->rcdev.of_reset_n_cells = 1;
> +	reset->rcdev.of_xlate = at91_reset_of_xlate;
> +
> +	return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
> +}
> +
>  static int __init at91_reset_probe(struct platform_device *pdev)
>  {
>  	const struct of_device_id *match;
> @@ -269,6 +361,10 @@ static int __init at91_reset_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, reset);
>  
> +	ret = at91_rcdev_init(reset, data, pdev);
> +	if (ret)
> +		goto disable_clk;
> +
>  	if (of_device_is_compatible(pdev->dev.of_node, "microchip,sam9x60-rstc")) {
>  		u32 val = readl(reset->rstc_base + AT91_RSTC_MR);
>  
> @@ -277,14 +373,16 @@ static int __init at91_reset_probe(struct platform_device *pdev)
>  	}
>  
>  	ret = register_restart_handler(&reset->nb);
> -	if (ret) {
> -		clk_disable_unprepare(reset->sclk);
> -		return ret;
> -	}
> +	if (ret)
> +		goto disable_clk;
>  
>  	at91_reset_status(pdev, reset->rstc_base);
>  
>  	return 0;
> +
> +disable_clk:
> +	clk_disable_unprepare(reset->sclk);
> +	return ret;
>  }
>  
>  static int __exit at91_reset_remove(struct platform_device *pdev)
> -- 
> 2.33.0
>